1. Field of the Invention
This invention relates to strap engaging and adjusting devices such as used for securing cargo and the like. More particularly, it relates to a strap tie down device which provides a combined winch-pulley effect and thus permits one to greatly increase the tension force in restraining the cargo.
Specifically, the invention relates to a new and highly efficient strap tie down device combining the winch-pulley effect which provides for the first time ability to apply tension forces of several hundred ft. lbs. in restraining the cargo, and which can be more universally utilized than many prior known devices. The new strap tie down device of the present invention broadly comprises an elongated rigid frame means comprising a base and spaced parallel side plate members attached perpendicular to opposite sides of said base, at both ends of said frame a set of at least two transverse extending connecting rods joined to both sides of said plate member above the base, which connecting rods being separated from each other by sufficient distance to permit a looping of the strap between said rods, which loops capable of being held in place by adding a removable connecting rod under the loop, a winch-type strap tightening means attached to said side plate members above the base and between the most inner connecting rod of both sets, said strap tightening means comprising a rotable shaft means for winding and unwinding the strap, slot means in the shaft means for receiving a portion of the strap, ratchet means associated with the shaft means for releasably holding the shaft means against unwinding rotation during and after the tension of the strap, and mans for permiting rotation of the shaft means to tighten the strap.
The invention further provides methods for using the new strap tie down device as described hereinafter.
2. Prior Art
There is a great variety of material that is now being shipped by trucks, trailers, open freight rail beds, and the like, and there is a great need for devices for securing the loaded objects, such as boxes, pipes, lumber, boats, furniture, etc. on the beds of the trucks, trailers and rail cars to prevent the cargo from shifting and causing damage to the goods and the vehicles involved.
In the past, various devices and apparatus have been suggested for such purpose. Such prior art devices and apparatus have included, for example, such simple devices as ropes or cords or straps and more complicated apparatus including various winch and ratchet mechanisms.
These prior art devices and apparatus, however, have many limitations which have prevented them from being accepted for many tie down applications. Most of such devices, for example, are limited by the amount of tension force that can be applied on the straps and cords, and this often permits the tie downs to loosen after a period of time. Other devices are not too secure and easily slip and loosen the cargo tie. Other devices are complicated and difficult to operate.
Examples of some of the more complicated prior art devices which have various limitations are disclosed and claimed in U.S. Pat. No. 3,826,473, U.S. Pat. No. 4,155,537, U.S. Pat. No. 3,180,623 and U.S. Pat. No. 4,510,652.
Many of such devices which are used on truck beds are either permanently attached or temporarily hooked to the side rail of a flatbed trailer. The permanent winches are seldom in the correct location for securing the load properly. For example, many times the best place for securing the load is over the wheel area where such devices cannot be located. The portable winches rely on the tension in the strap securing the load to keep it hooked on the trailer. If the load shifts or settles, the slack releases the tension in the strap and the portable winch becomes unhooked. Quite often, the portable winch slips off many times while threading the strap through it before it is tight enough to secure the load and keep it hooked down on its narrow side rail edge.
Many of the devices, such as shown in U.S. Pat. No. 3,826,473, require the two ends of the strap to be placed in the wind-up mechanism and this causes the mechanisms to fill twice as fast and in many cases prevents effecting the proper tension.
Other devices, such as shown in U.S. Pat. No. 4,510,652 use a strap tightening device with a plate, and when the strap is tight, the plate is nailed down and the device used on another strap. This type of arrangement presents problems in loosening the strap for unloading as well as possibilities of slipping during movement of the trailer.
It is an object of the invention, therefore, to provide a new type of strap tie down device which avoids many of the above-noted problems. It is a further object to provide a new type of strap tie down device which permits one to greatly increase the tension force to be applied in restraining the cargo. It is a further object to provide a new strap tie down device which can be easily applied to any location on the truck or trailer to restrain the cargo. It is a further object to provide a new strap tie down device which has good security and does not loosen or slip on movement of the cargo. It is a further object to provide a new type of strap tie down device which is easy to operate on any size or type of cargo to be secured. It is a further object to provide a new type of strap tie down device which is economical to make and free of repair. These and other objects of the invention will be apparent from the following detailed description thereof.